Lifter problem

kvnhpnr · 12-16-2009, 07:02 PM

I have a major problem...I was told that I didn't have a lifter knocking like I thought initially but instead I was told that I have what he referred to as "ROD SLAP" is this a minor or a major problem to repair. What doe THIS entail?

Icey1174 · 12-17-2009, 05:03 AM

Did you have a reputable place diagnosis this "rod slap?" The fuel injectors make a lot of noise and I had local shops tell me everything from lifters to rods. Turns out it was always the injectors. The injectors do make a lot of noise just like ticking lifters.

I would guess "rod slap" to be bad rob bearings if that's really the problem. The rod bearings are pretty easy to replace, just somewhat time consuming.

Any other input/ideas?

John_AZ · 12-17-2009, 05:40 AM

Quote:

Originally Posted by Icey1174

I would guess "rod slap" to be bad rob bearings if that's really the problem. The rod bearings are pretty easy to replace, just somewhat time consuming.

Any other input/ideas?

Icey1174 is being kind in saying that the job is "somewhat" time consuming.

Rod bearings are damaged-usually #2, if coolant and oil mix or oil pressure fails.
Any engine at 125K +- should replace the rod bearings as normal maintenance.

You could try SeaFoam to make sure the lifters are not the clicking noise. Follow the can instructions. You will have to drain the oil if you continue to do the rod bearings anyway.

To get to the rod bearings, the oil pan is removed.
To remove the oil pan, the crossmember and PS rack are removed.

Here are a couple of threads to explain better from TexasBlake and others.

Cross Member - Porsche 951 - www.texasblake.com
Rod Bearings - Porsche 951 - www.texasblake.com
Clark's Garage Message Board :: View topic - Crankcase gasket replacement hint
Paragon Products - Tech Session - Porsche Tech and Information

GL
John_AZ

Icey1174 · 12-17-2009, 08:16 AM

Yes, there is a fair amount of work to replace them. Nothing that is overly difficult. The good news is you can do some other things while you're in there like the oil pan gasket.

Slam · 12-17-2009, 01:11 PM

...and the motor mounts!

The injectors make the car sound like a sewing machine. Anything worse/louder is usually a bad thing. I agree about trying to clean the lifters with an oil additive, but if you truly have rod slap you may be in for a headache. The rod bearings are pretty easy to do as long as the crank is okay, but usually by the time you've got rod noise the crank is toast.

krystar · 12-17-2009, 03:15 PM

first question is: is there truely rod knock? cause definitively diagnosing the problem as rod knock is not a simple proposition.

i wouldn't put it past the shop to say "oh yea it's rod knock, we're gonna have to tear engine apart. estimate is 3 grand in labor"

HondaDustR · 12-17-2009, 10:59 PM

If it's rod knock and bad enough to hear, wouldn't the oil pressure bounce around on hot idle, and dip under load at lower rpm? Another way to tell is if you rev the motor so it's knocking, hold the brake, load the motor down by slipping the clutch and see if it gets louder.

Lifters often go flat and they do make a very disturbing metal tapping noise, but it doesn't change with engine load like rod knock would, it doesn't really affect oil pressure, and sometimes it fades in and out depending on how bad the lifter is.